1. Field of the Invention
The present invention relates to processing image data defined by a hierarchical structure of data processing nodes.
2. Description of the Related Art
Many post production processes have been devised and employed over the years to enhance movie productions or video films with what is commonly referred to as “special effects”. Such image enhancement have long been provided by means of using dedicated hardware, either as a scale model to be filmed and subsequently composited in post production or, more recently, by means of effects generators such as computer apparatus configured to output rendered image components to be also subsequently composited.
Technical advances in image processing systems have enabled the generalisation of the “blue screen” technique in video environments and “green screen” technique in cinematographic environments, whereby actors are filmed in a studio configured with blue or green saturated surroundings in order to generate a clip of foreground image frames. An alternative clip of background image frames is subsequently generated and a compositing process allows an editor to seamlessly blend the foreground and background image frames by means of keying part of the corresponding video signals, for instance the luminance or chrominance signal.
A problem inherent to the above image processing techniques was that effects generation could not take place in real-time, that is all of the various components in each image frame within a clip of such image frames would have to be shot in the case of real actors and/or situations committed to cinematographic film, or rendered in the case of computer graphics images, prior to the compositing process. Thus, if the appearance of any of such image components was artistically unsatisfactory, the only possible manner of remedying this problem would be to do another shot on new cinematagraphic film or amend parameters in the computer to generate a new version of the computer-rendered image components.
Modern image processing systems overcome the above problem by means of providing real-time image data processing capability, whereby every image component within an image frame exists as a hierarchical sub-structure of data processing nodes within a main structure, which thus defines the entire image frame. An image editor using such a modern image processing system can amend parameters and/or data in any of said data processing nodes to aesthetically improve any image component within an image frame and assess the effectiveness of his editing in real-time.
A problem has however developed within modern image processing systems as described above. As the size of modern movie image frames or high definition video image frames has dramatically increased, both in resolution and in the number of components therein, their corresponding structure of data processing nodes and further user-operable controls to edit the data and/or parameters of said nodes in said image processing systems has also grown. Indeed; conventional display devices of image processing systems can barely accommodate such image frames at full resolution, which often exceeds 2000 by 2000 pixels. Moreover, a structure of data processing nodes corresponding to any such image frame often includes hundreds or even thousands of such nodes, to the extent that the readability of such a structure becomes problematic from a user's point of view when displayed as an alternative to said image frame.